/Engine/Source/Runtime/UMG/Public/Blueprint/UserWidget.h
Returns the BlueprintGeneratedClass that generated the WidgetTree. A child UserWidget that extends a parent UserWidget will not have a new WidgetTree. The child UserWidget will have the same WidgetTree as the parent UserWidget. This function returns the parent UserWidget's BlueprintClass.
[UWidgetBlueprintGeneratedClass](API\Runtime\UMG\Blueprint\UWidgetBlueprintGeneratedClass) * GetWidgetTreeOwningClass() const